<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <div class="loading"></div>

  <style>
    @keyframes loading {

      0%,
      33.33% {
        content: ".";
      }

      33.34%,
      66.66% {
        content: "..";
      }

      66.67%,
      100% {
        content: "...";
      }
    }

    .loading::after {
      content: ".";
      display: inline-block;
      animation: loading 1s steps(1, end) infinite;
    }
  </style>
</body>

</html>